Method of manufacturing a surface treated member for semiconductor liquid crystal manufacturing apparatus

ABSTRACT

A method of manufacturing a surface treated member used for semiconductor liquid crystal manufacturing apparatus, capable of forming an anodized film at a higher hardness than that of an anodizing film formed of an existent method, with no problem in view of the generation of cracks, and excellent in the balance between a high hardness and reduced cracks by a simple and convenient method by forming an anodized film to the surface of a member having an aluminum alloy or pure aluminum as a basic material, then dipping the same in pure water, and applying a hydrating treatment to the anodized film, wherein the hydrating treatment is conducted under the conditions satisfying that a treatment temperature is 80° C. to 100° C. and a treatment time (min)≧−1.5×treatment temperature (° C.)+270.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a method of manufacturing a surface treated member used for semiconductor liquid crystal manufacturing apparatus having an aluminum alloy or pure aluminum as a basic material used suitably as a material for vacuum chambers, for example, of manufacturing facilities for semiconductors and liquid crystals such as dry etching apparatus, CVD apparatus, ion implantation apparatus, and sputtering apparatus, or for part disposed in the inside of the vacuum chambers.

2. Description of the Related Art

An anodizing treatment of forming an anodized film to the surface of a member having an aluminum alloy or pure aluminum as a basic material thereby providing the basic material with plasma resistance or gas corrosion resistance has been known generally so far.

For example, a vacuum chamber used for plasma processing apparatus of semiconductor manufacturing facilities, as well as various members such as electrodes disposed to the inside of the vacuum chambers have usually been formed by using aluminum alloys. However, when the aluminum alloy is used as it is with no treatment, plasma resistance or gas corrosion resistance cannot be maintained. Therefore, an anodizing treatment has been applied as a countermeasure to the surface of a member formed of an aluminum alloy to form an anodized film, thereby providing plasma resistance or gas corrosion resistance.

Since the vacuum chamber used for the plasma treatment apparatus of semiconductor manufacturing facilities, as well as various members such as electrodes disposed to the inside of the vacuum chamber suffer from severe wearing at the anodized film due to the physical energy of plasmas, it is necessary that the anodized film has a high hardness. Further, if cracks are present in the anodized film, since gases intrude through the cracks to erode the aluminum alloy as a basic material, it is desired that cracks are not present in the anodized film as much as possible.

As a method of increasing the hardness of the anodized film, a method of controlling an electrolyte to a low temperature upon forming the anodized film or a method of performing electrolysis at a high current density has been adopted so far. However, when the hardness of the anodized film is increased by the method described above, this tends to increase the generation of the cracks in the anodized film and, in addition, the method also involves a problem of requiring high energy. In view of the above, while the balance has been conditioned between the hardness and the cracks of the anodized film depending on the working circumstance and the required cost for various members, it cannot sufficiently cope with the requirements for high hardness, reduced cracks, and cost.

Further, as a method of increasing the hardness of the anodized film, JP-A No. 2006-336081 proposes a method of forming an anodized film of a high hardness by using a sulfuric acid type electrolyte with addition of an alcohol. However, the method involves a problem of complicating the control for the change of the concentration of the alcohol in the electrolyte by the anodizing treatment.

Further, JP-A No. 2004-332081 proposes a method of forming a flame sprayed oxide film further on the surface of a surface treated member in which anodization is applied to an aluminum alloy and it describes that the obtained film has high hardness. However, the method involves a problem of extremely complicating the treatment for forming the flame sprayed oxide film, requiring an expensive facility, and not capable of being applied to a portion of a complicated shape.

SUMMARY OF THE INVENTION

The present invention has been achieved for solving the problems in the prior art described above and intends to provide a method of manufacturing a surface treated member used for semiconductor liquid crystal manufacturing apparatus capable forming an anodized film having a higher hardness than that of the anodized film farmed by the existent method, with no problem also in view of the generation of cracks, and excellent in the balance between the high hardness and the reduced cracking by a simple and convenient method.

The present invention provides, in a first aspect, a method of manufacturing a surface treated member used for semiconductor liquid crystal manufacturing apparatus by forming an anodized film on the surface of a member having an aluminum alloy or pure aluminum as a basic material and then applying a hydrating treatment to the anodized film while immersing the film in purified water, wherein the hydrating treatment is conducted under the condition of satisfying that a treatment temperature is from 80° C. to 100° C., and a treatment time (min)≧−1.5×treatment temperature (° C.)+270.

The present invention provides, in a second aspect, a method of manufacturing a surface treated member used for semiconductor liquid crystal manufacturing apparatus according to the first feature, wherein a heat treatment is conducted after the hydrating treatment under the condition of satisfying: a treatment temperature is from 120° C. to 450° C., and a treatment time (min)≧−0.1×treatment temperature (° C.)+71.

According to the first aspect of the method of manufacturing the surface treated member used for semiconductor liquid crystal manufacturing apparatus, an anodized film having a higher hardness than that of the anodized film formed by the existent method, with no problems also in view of the generation of cracks, and excellent in the balance between a high hardness and a reduced cracks by an extremely simple and convenient method of defining the treatment time and the treatment temperature for the hydrating treatment.

Further, the hydrating treatment in the method of manufacturing the surface treated member used for semiconductor liquid crystal manufacturing apparatus of the invention is a treatment using hot water at a treatment temperature of 80° C. to 100° C. and it requires no special facility as in the hydrating treatment using pressurized steams.

According to the second aspect for the method of manufacturing the surface treated member used for the semiconductor liquid crystal manufacturing apparatus, since the heat treatment is applied further after the hydrating treatment, the hardness of the anodized film can be increased further within a range not causing a problem also in view of the generation of cracks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph collectively showing the test result of an example that shows a relation of the time for a hydrating treatment and the temperature for the hydrating treatment to a Vickers hardness;

FIG. 2 is a graph collectively showing the test result of an example that shows a relation of the time for a hydrating treatment and a treatment temperature for the hydrating treatment, to a frequency of cracks; and

FIG. 3 is a microscopic photograph showing the situation for the generation of cracks in an observation example in which the surface of a test specimen is observed by an optical microscope at a factor of 400× in the example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is to be described specifically with reference to preferred embodiments.

An anodized film is formed by dipping a basic material such as an aluminum alloy in an electrolyte as an anode and supplying a current therethrough to oxidize the surface of the basic material such as an aluminum alloy on the side of the anode. Properties of an anodized film formed, i.e., hardness of the anodized film, frequency of cracks to be generated, etc. are different depending on the composition of the electrolyte, the electrolysis temperature, and the current density (current value per unit area).

The anodized film is formed at present mainly by using a sulfuric acid electrolyte and performing electrolysis at a low temperature and at a high current density. However, when the anodized film is formed by the method, it produces confliction that an anodized film of high hardness can be obtained but the frequency of cracks (for example, length of cracks per unit surface area) generated in the anodized film is increased.

Further, in the surface treated member used for the semiconductor liquid crystal manufacturing apparatus, a hydrating treatment is sometimes applied to the anodized film (usually referred to as a pore sealing treatment) with a view point of restraining the chemical reaction between a gas and an anodized film. However, it is generally known that the hardness of the anodized film is lowered when the hydrating treatment is applied as described, for example, in JP-A No. 07-216588 as “the pore sealed layer 4 formed by the pore sealing treatment tends to be crystallized, which causes lowering of the film strength”, and the time for hydrating treatment was set within such a range as permitting the lowering of the hardness.

The present inventors have noted on the hydrating treatment and made earnest studies and investigations. As a result, it has been revealed that when the time for the hydrating treatment is made sufficiently longer, the hardness of the anodized film is rather increased and the frequency for the generation of cracks is not increased so much, and the present invention has been accomplished.

Specifically, the hardness of the anodized film is increased and the frequency for the generation of cracks is not increased so much by performing the hydrating treatment so as to satisfy the condition that the treatment time is defined as for 80° C. to 100° C. upon hydrating the anodized film and the treatment time upon applying the hydrating treatment as: “treatment time (min)≧−1.5×treatment temperature (° C.)+270”.

Further, it has also been revealed that the hardness of the anodized film is further increased and the frequency for the generation of cracks is not increased to such a level as causing a problem by applying a heat treatment after the hydrating treatment.

The specific condition for the heat treatment is to apply the heat treatment to the anodized film so as to satisfy the condition that the treatment temperature is defined as from 120° C. to 450° C. and the treatment time upon applying the heat treatment as: “treatment time (min)≧−0.1×treatment temperature (° C.)+71”. When the heat treatment is applied to the anodized film under the condition described above, the hardness can be increased further by Hv 25 or higher by virtue of the Vickers hardness than that of the anodized film increased for the hardness before applying the heat treatment.

(Treatment Temperature for Hydrating Treatment)

The temperature for the hydrating treatment is defined as within a range from 80° C. to 100° C. In a case where the temperature for the hydrating treatment is lower than 80° C., the hardness of the anodized film is not increased even when the hydrating treatment is applied for the treatment time capable of satisfying the condition as: “treatment time (min)≧−1.5×treatment temperature (° C.)+270”. While the reason has not yet been analyzed sufficiently, this is considered to be attributable to that the state of oxides in the anodized film formed by hydration reaction is different from that at 80° C. or higher. On the other hand, special equipment, for example, of converting water into steams becomes necessary in order to raise the temperature for the hydrating treatment to higher than 100° C.

The temperature for the hydrating treatment is preferably as high as possible within the range up to 100° C. since the treatment time is shortened which is excellent in view of production. On the other hand, as the temperature is higher, the evaporation amount of water increases, which requires supplement of water and complicates the treatment. Further, since water at 80° C. or higher used in separate facilities in a plant can be diverted, the temperature for the hydrating treatment may be determined properly within a range from 80° C. to 100° C. with the view point described above.

(Treatment Time for Hydrating Treatment)

Even when the treatment temperature for the hydrating treatment is defined as within a range from 80° C. to 100° C., since the hardness of the anodized film is lowered conversely if the treatment time is short, it is necessary to define the minimum treatment time depending on the treatment temperature. Specifically, the hydrating treatment may be performed so as to satisfy the condition that “treatment time (min)≧−1.5×treatment temperature (° C.)+270”. Although the reason why the hardness of the anodized film changes depending on the time for the hydrating treatment has not yet been analyzed sufficiently, this may be considered to be attributable to the balance between the change of state of the oxides and the volume expansion of the oxides in the anodized film by the hydration reaction.

While the hardness of the anodized film is increased by setting the treatment time for the hydrating treatment as long as possible within a range satisfying the condition that “treatment time (min)≧−1.5×treatment temperature (° C.)+270”, since the frequency of cracks tends to increase though it occurs only slightly, the treatment time may be determined appropriately in accordance with the required performance. However, since the productivity is deteriorated when the treatment time is excessively long, the treatment time for the hydrating treatment is preferably 480 min or less and, more preferably, 300 min or less.

(Treatment Time for Heat Treatment)

The temperature for the heat treatment is defined as within a range from 120° C. to 450° C. In a case where the temperature for the heat treatment is lower than 120° C., the hardness of the anodized film is not increased even when the heat treatment is applied for a treatment time capable of satisfying the condition that “treatment time (min)≧−0.1×treatment temperature (° C.)+71”. Although the reason has not yet been analyzed sufficiently, this is considered to be attributable to that the structural change of the anodized film along with the dehydration reaction after the hydration reaction is insufficient. On the other hand, in a case where the temperature for the heat treatment is higher than 450° C., aluminum alloys, etc. as the basic material tend to deform, whereby the product possibly deviates from the dimensional tolerance. Accordingly, the temperature for the heat treatment is defined as within a range from 120° C. to 450° C.

(Treatment Time for Heat Treatment)

Even when the treatment time for the heat treatment is defined as within a range from 120° C. to 450° C., if the treatment time is short, the hardness of the anodized film is increased only to about Hv. 20 or less by virtue of the Vickers hardness to provide no substantial industrial merit of applying the heat treatment, so that the minimum treatment time may be defined depending on the treatment temperature. Specifically, the heat treatment may be performed so as to satisfy the condition that “treatment time (min)≧−0.1×treatment temperature (° C.)+71”. While the reason why the hardness of the anodized film changes depending on the time for the heat treatment has not yet been analyzed sufficiently, this can be considered to be attributable to the structural change of the anodized film along with the dehydration reaction after the hydration reaction.

While the hardness of the anodized film increases when the treatment temperature for the heat treatment is set as long as possible within a range satisfying the condition that “treatment time (min)≧−0.1×treatment temperature (° C.)+71”, the frequency of cracks tends to increase on the other hand though this may occurs only slightly. Accordingly, the treatment temperature may be determined in accordance with the required performance. However, since the productivity is deteriorated when the treatment time is excessively long, the treatment time for the hydrating treatment is preferably 120 min or less and, more preferably, 90 min or less.

Example

The present invention is to be described more specifically with reference to examples but the invention is not restricted by the following examples and appropriate modifications may be applied in a range capable of conforming to the gist of the invention and any of them is included within a technical scope of the invention.

At first, a 6061 aluminum alloy according to JIS was melted into a cast ingot of an aluminum alloy (size: 220 mmW×250 mmL×t100 mm, cooling rate: 15 to 10° C.), the cast ingot was cut and ground on the surface (size: 220 mmW×150 mmL×t60 mm) and then applied with a soaking treatment (540° C.×4 h). After the soaking treatment, the material of 60 mm thickness was rolled into a plate material of 6 mm thickness by hot rolling and cut (size: 220 mmW×400 mmL×t6 mm) and then applied with a solid solution treatment (510 to 520° C.×30 min). After the solid solution treatment, it was water-hardened and applied with an aging treatment (160 to 180° C.×8 h) to obtain a test alloy plate.

A test specimen of 25 mm×35 mm (rolling direction)×t3 mm was cut out from the test alloy plate and the surface was ground. Then, after dipping into an aqueous 10% NaOH solution at 60° C. for 2 min, the test specimen was washed with water, further dipped in an aqueous 20% HNO₃ solution at 30° C. for 2 min, then washed with water to clean the surface, and applied with an anodizing treatment under each of conditions shown in Tables 1 to 4 to form an anodized film on the surface of the test specimen. The thickness for all of the anodized films was 50 μm.

Further, the hydrating treatment was performed by dipping each of the test specimens in pure water at each of temperatures for the hydrating treatment and for each of times for hydrating treatment.

Further, a heat treatment was applied to several test specimens. The heat treatment was performed while placing each of the test specimens in an atmospheric heat treatment furnace at each of heat treatment temperatures and for each of heat treatment times shown in Tables 1 to 4.

The surface for each of the test specimens prepared by the method described above was observed by an optical microscope at a factor of 400× to determine the frequency of cracks. FIG. 3 shows the microscopic photograph for an observation example. The frequency of cracks was determined by measuring the total length (mm) of the cracks generated within a range of 0.235×0.180 mm for the surface of each of the test specimens and converting the total length to the unit of mm/mm².

Then, each of the test specimens was buried in a resin, the cross section of the anodized film was exposed and then the hardness at a central portion for the cross section of the anodized film was measured by Vickers hardness meter (Akashi, MVK-G2).

For each of the test specimens after the hydrating treatment, those having Vickers hardness obtained by the measurement for each of the test specimens which was higher than the Vickers hardness for No. 1 not applied with the hydrating treatment were considered that the anodized film had a high hardness and evaluated as “acceptable”. Further, for each of the test specimens after the heat treatment, those having Vickers hardness obtained by the measurement for each of the test specimens which was increased by Hv. 25 or more than the Vickers hardness before the heat treatment were considered that the anodized film had a high hardness and evaluated as “acceptable”.

Tables 1 to 4 show the result of the test, in which FIG. 1 shows the relation of the hydrating treatment time and the hydrating treatment temperature, to the Vickers hardness for No. 1 to No. 29 and a relation of the hydrating treatment time and the hydrating treatment temperature, to the Vickers hardness for No. 32 to No. 43, and FIG. 2 shows a relation of the hydrating treatment time and the hydrating treatment temperature, to the crack density for No. 1 to No. 29, and a relation of the hydrating treatment time and the hydrating treatment temperature, to the crack density for No. 32 to No. 43, respectively.

TABLE 1 Hydrating treatment Film formation Hydrating −1.5 × Heat treatment Result of test Treatment Electrolysis treatment treatment Heat Frequency solution current tem- tempera- Hydrating treatment Heat Vickers of cracks Anodization temperature density perature ture + treatment temperature treatment hardness (mm/ No. Remarks solution (° C.) (A/dm²) (° C.) 270 (min) time (min) (° C.) time (min) (Hv.) mm²) 1 Comparative Sulfuric acid 0 2.0 With no hydrating treatment — — 452 8 example 150 g/L 2 Comparative 100 120 30 — — 434 9 example 3 Comparative 60 — — 433 10 example 4 Comparative 90 — — 432 11 example 5 Comparative 100 — — 441 11 example 6 Comparative 110 — — 448 11 example 7 Example 120 — — 471 12 8 Example 180 — — 495 13 9 Example 240 — — 502 15 32 Example 240 120 60 531 17 33 Example 240 300 60 574 20 34 Example 240 400 60 651 22 35 Comparative 240 120 30 520 15 example 36 Comparative 240 300 25 518 15 example 37 Comparative 240 400 10 522 15 example

TABLE 2 Hydrating treatment Film formation Hydrating −1.5 × Heat treatment Result of test Treatment Electrolysis treatment treatment Heat Frequency solution current tem- tempera- Hydrating treatment Heat Vickers of cracks Anodization temperature density perature ture + treatment temperature treatment hardness (mm/ No. Remarks solution (° C.) (A/dm²) (° C.) 270 (min) time (min) (° C.) time (min) (Hv.) mm²) 1 Comparative Sulfuric acid 0 2.0 With no hydrating treatment — — 452 8 example 150 g/L 10 Comparative 90 135 30 — — 435 9 example 11 Comparative 60 — — 430 9 example 12 Comparative 100 — — 432 10 example 13 Comparative 120 — — 445 10 example 14 Example 135 — — 461 10 15 Example 180 — — 484 11 16 Example 240 — — 494 12 38 Example 240 120 60 524 13 39 Example 240 300 60 563 16 40 Example 240 400 60 635 18

TABLE 3 Hydrating treatment Film formation Hydrating −1.5 × Heat treatment Result of test Treatment Electrolysis treatment treatment Heat Frequency solution current tem- tempera- Hydrating treatment Heat Vickers of cracks Anodization temperature density perature ture + treatment temperature treatment hardness (mm/ No. Remarks solution (° C.) (A/dm²) (° C.) 270 (min) time (min) (° C.) time (min) (Hv.) mm²) 1 Comparative Sulfuric acid 0 2.0 With no hydrating treatment — — 452 8 example 150 g/L 17 Comparative 80 150 30 — — 432 8 example 18 Comparative 60 — — 428 9 example 19 Comparative 120 — — 425 9 example 20 Comparative 140 — — 445 9 example 21 Example 150 — — 458 9 22 Example 180 — — 462 10 23 Example 240 — — 468 10 41 Example 240 120 60 498 11 42 Example 240 300 60 533 12 43 Example 240 400 60 598 14

TABLE 4 Hydrating treatment Film formation Hydrating −1.5 × Heat treatment Result of test Treatment Electrolysis treatment treatment Heat Frequency solution current tem- tempera- Hydrating treatment Heat Vickers of cracks Anodization temperature density perature ture + treatment temperature treatment hardness (mm/ No. Remarks solution (° C.) (A/dm²) (° C.) 270 (min) time (min) (° C.) time (min) (Hv.) mm²) 1 Comparative Sulfuric acid 0 2.0 With no hydrating treatment — — 452 8 example 150 g/L 24 Comparative 70 165 30 — — 442 8 example 25 Comparative 60 — — 438 8 example 26 Comparative 90 — — 433 8 example 27 Comparative 120 — — 430 9 example 28 Comparative 180 — — 429 9 example 29 Comparative 240 — — 430 9 example 30 Comparative −10 4.0 With no hydrating treatment — — 493 32 example 31 Comparative 100 — 30 — — 475 33 example

According to Tables 1 to 4, the frequency of cracks obtained in the test is not high and the Vickers hardness satisfies the acceptance/rejection criteria in No. 7 to No. 9, No. 14, to No. 16, No. 21 to No. 23 as examples of the invention that satisfy the requirement for the hydrating treatment of the invention in which the treatment temperature for the hydrating treatment is defined as 80° C., 90° C., and 100° C., and the treatment time satisfies the condition: “treatment time (min)≧−1.5×treatment temperature (° C.)+270”.

On the other hand, the hardness of No. 2 to No. 6, No. 10 to No. 13, and No. 17 to No. 20 in which the treatment temperature for the hydrating treatment is defined as 80° C., 90° C., and 100° C., but not satisfying the condition that “treatment time (min)≧−1.5×treatment temperature (° C.)+270” is smaller than the Vickers hardness of No. 1 as a comparative example not applied with the hydrating treatment.

Further, the hardness of No. 24 to No. 29 setting the treatment temperature for the hydrating treatment at 70° C. is smaller than the Vickers hardness for No. 1 as the comparative example not applied with the hydrating treatment, irrespective of the fact that the condition: “treatment time (min)≧−1.5×treatment temperature (° C.)+270” is satisfied or not.

No. 30 and No. 31 are examples of forming the anodized films by an existent hardness increasing method (treatment at low temperature and high current density). Although the Vickers hardness is about identical with that of Nos. 7, 8, 15, and 16, the frequency of cracks is much higher and deteriorated compared with them. On the other hand, Nos. 2, 3, 10, 11, 17, 18 correspond to the existent anodized film with importance being attached to the frequency of cracks but the Vickers hardness is small as described above. That is, an anodized film having higher hardness than that of the anodized film formed by the existent method and with no problem also in view of the generation of cracks can be formed by satisfying the condition for the hydrating treatment that “treatment time (min)≧−1.5×treatment temperature (° C.)+270”.

Further, Nos. 32 to 43 are test specimens applied with the heat treatment after the hydrating treatment. According to Tables 1 to 4, in No. 32 to 34, No. 38 to No. 43 as examples of the invention that satisfy the requirement of the heat treatment according to the invention in which the treatment temperature for the heat treatment is defined as 120° C., 300° C., 400° C., and the treatment time satisfies the condition that “treatment time (min) ≧−0.1×treatment temperature (° C.)+71”, the frequency of cracks obtained by the test is much lower than that of No. 30 and No. 31 of forming the anodized film by the existent hardness increasing method, frequency of generation of cracks does not cause problems, and the Vickers hardness satisfies the acceptance/rejection criteria.

On the other hand, the Vickers hardness does not increase by Hv. 25 or more in No. 35 to No. 37 in which the treatment temperature for the heat treatment is defined as 120° C., 300° C., 400° C., but not satisfying the condition that “treatment time (min)≧−0.1×treatment temperature (° C.)+71” compared with that before the heat treatment.

Summarizing the test results described above, it can be confirmed that an anodized film having a higher hardness than that of the anodized film formed by the existent method, with no problem in view of the generation of cracks, and excellent in the balance between the high hardness and the reduced cracks can be formed by manufacturing a surface treated member used for the semiconductor liquid crystal manufacturing apparatus under the conditions satisfying the requirements of the invention by a simple and convenient method. 

1. A method of manufacturing a surface treated member used for semiconductor liquid crystal manufacturing apparatus by forming an anodizing film to the surface of a member having an aluminum alloy or pure aluminum as a basic material and then dipping the same in pure water, thereby applying a hydrating treatment to the anodized film, wherein the hydrating treatment is conducted under the conditions satisfying that a treatment temperature is from 80° C. to 100° C., and a treatment time (min)≧−1.5×treatment temperature (° C.)+270.
 2. A method of manufacturing a surface treated member used for semiconductor liquid crystal manufacturing apparatus according to claim 1, wherein a heat treatment is conducted after the hydrating treatment under the conditions satisfying that a treatment temperature is from 120 to 450° C., and a treatment time (min)≧−0.1×treatment temperature (° C.)+71. 